OS X 10.10.4

Mac OS X 10.10.4 was an update to Mac OS X 10.10 released on June 30, 2015. It has the following features:
The OS X Yosemite v10.10.4 update improves the stability, compatibility, and security of your Mac.

This update includes the following:

Improves networking reliability

Improves Migration Assistant reliability

Addresses an issue that prevented some external displays from functioning properly

Improves the reliability of upgrading iPhoto and Aperture libraries to Photos